When stray current from the concrete floor of a farm building flows through the body of an animal to reach the metallic structures of that farm building and their grounding connection network, the animal(s) feels this stray current. The animal(s) is affected and has a physiological reaction resulting into abnormal health conditions.
As an example, the physiological reaction of a man when an electric current flows through his body (hand-trunk-foot) can be summarized as follows:
perception threshold: 1--3 mA (duration of 1 sec); PA1 strong sensation threshold: 3.5-8 mA (duration of 1 sec); PA1 contraction and release threshold: 8-15 mA (duration of 1 sec); PA1 fibrillation current threshold: 30 mA and more (duration of 1 sec). PA1 means for sensing the alternating stray current flowing through the ground return circuit; PA1 means for producing a signal representative of the sensed stray current; means for generating, in response to the current representative signal, an alternating compensatory current having an amplitude substantially equal to the amplitude of the sensed stray current and being out of phase with respect to the stray current by an angle substantially equal to 180.degree.; and PA1 means for injecting the alternating compensatory current in the ground return circuit. PA1 sensing the alternating stray current flowing through the ground return circuit; PA1 producing a signal representative of the sensed stray current; PA1 generating, in response to the current representative signal, an alternating compensatory current having an amplitude substantially equal to the amplitude of the sensed stray current and being out of phase with respect to the stray current by an angle substantially equal to 180.degree.; and PA1 injecting the alternating compensatory current in the ground return circuit whereby the stray current and the compensatory current add together and substantially cancel each other.
The symptoms specific to each species can be seen when stray current is flowing.
For example, cows will refuse to give their milk and to enter in the cowshed. They may also paw the ground and kick the milker. In the most critical situations, the cows present problems of mastitis, of reproduction, of leucocyte, etc.
Pigs can present similar symptoms; cases of cannibalism and mastitis, and problems of diarrhoea, of temperature and of constipation can be found. In the most critical cases, the dead-rate of the little pigs may considerably increase.
Regarding fish breeding basins, stray current may cause luxation of the vertebral column of the fish and will greatly stress the fish to cause repeated furunculosis epidemic.